1. Field of the Invention
The present invention relates to a brake pad wear detecting apparatus, in details, to a brake pad wear detecting apparatus having a probe case attached to a back plate and a probe fixedly positioned to a predetermined position relative to a lining by being mounted to the probe case for detecting wear of a brake pad and outputting a constant wear detecting signal by bringing a rotating member into contact with a front end of the probe when a wear amount of the lining reaches a predetermined value.
2. Description of the Related Art
There has been proposed a brake pad wear detecting apparatus mounted to a brake apparatus of a vehicle, outputting a constant wear detecting signal when a wear amount of a lining of a brake pad reaches a predetermined value and outputting an alarm urging replacement of the brake pad before the wear amount of the lining exceeds a limit.
FIG. 7 through FIG. 9 show a conventional example of such a brake pad wear detecting apparatus.
A brake pad wear detecting apparatus 10 shown here is disclosed in Japanese Utility Model Publication No. 42665/1983. The brake pad wear detecting apparatus 10 is provided with a probe case 6 attached to a back plate 4 fixedly mounted to a back face of a lining 3 of the brake pad 1. A probe 8 is fixedly positioned to a predetermined position relative to the lining 3 by mounting to the probe case 6 for detecting wear. The brake pad wear detecting apparatus 10 outputs a constant wear detecting signal by bringing a rotating member (disc rotor), not illustrated, into contact with a front end 8a of the probe 8 when a wear amount of the lining 3 reaches a predetermined value by being brought into contact with the rotating member.
The brake pad 1 is constituted by the lining 3 pressed to a surface of the rotating member for generating predetermined frictional force and the back plate 4 fabricated by a metal plate fixedly mounted to the back face side of the lining 3 for functioning as an attachment metal piece for a support member on the vehicle body side. The brake pad 1 is supported to be able to press the rotating member by hanging ear portions thereof formed to project at both side portions of the back plate 4 by a pad guide portion of a support member on the vehicle body side, although not illustrated.
As shown by FIG. 8, the probe case 6 in the conventional brake pad wear detecting apparatus 10 is constructed by a constitution formed with a flange portion 6b having a diameter larger than that of an attaching hole 4a at a front end of a cylindrical portion 6a capable of being inserted into the attaching hole 4a formed at the back plate 4 and mounted with an elastic locking piece 6c projected to an inner side at a middle portion of the cylindrical portion 6a. 
According to the probe case 6, the cylindrical portion 6a is inserted into the attaching hole 4a from the surface side of the back plate 4 before forming the lining 3 on the back plate 4 in a laminated state. The flange portion 6b is brought into a state of being in contact with the surface of the back plate 4 and thereafter, the lining 3 is formed on the surface of the back plate 4 in such a state to thereby sandwich the flange portion 6b by the lining 3 and the back plate 4 to fix to the back plate 4 as shown by FIG. 7.
The probe 8 is formed with faced portions 8c for engaging with the elastic locking pieces 6c at opposed positions of an outer periphery on a base end side of a main body 8b of a cylindrical shape. The probe 8 is inserted into the cylindrical portion 6a of the probe case 6, and when the main body 8b is inserted into the probe case 6 until a front end 8a thereof is brought into contact with a wear detecting position 3a of the lining 3, as shown by FIG. 7, the elastic locking pieces 6c are engaged with the faced portions 8c and fixed to the probe case 6.
Further, when the probe 8 is rotated relative to the probe case 6 in the state of being engaged with the probe case 6 as shown by FIG. 7, the elastic locking pieces 6c are pushed back by an outer peripheral face which is not faced. Then, engagement between the elastic locking pieces 6c and the faced portions 8c is disengaged and the probe 8 can be extracted from the probe case 6.
However, according to the above-described conventional brake pad wear detecting apparatus 10, since the probe case 6 is fixed to the back plate 4 in steps of fabricating the brake pad 1, there poses a problem that in the steps of fabricating the brake pad 1, it is necessary to integrate a mechanism of positioning the probe case 6 or the like and the steps of fabricating the brake pad 1 are complicated.
Further, since the probe case 6 is integrated to the brake pad 1, there also poses a problem that in replacing the brake pad, the probe case 6 cannot be utilized again.
Further, since the brake pad 1 is in a mode in which the probe case 6 is projected to the back face, the brake pads 1 cannot be stored to, overlap. Accordingly, a large store space is needed and at the same time, and there is a concern that other article hits the probe case 6 in carrying the brake pad 1 and the probe case 6 is damaged. Further, there also poses a problem that the storing performance and handling performance are poor.
The present invention has been carried out in view of the above-described situation and it is an object thereof to provide a brake pad wear detecting apparatus in which steps of fabricating a brake pad is not complicated. Further, a probe case can be simply attached to and detached from a back plate; therefore, when the brake pad is replaced, the probe case can be simply removed from a used brake pad and utilized again. Further, in storing or carrying the brake pad, by bringing the probe case into a state of being removed from the brake pad, a number of pieces of the brake pads can be stored or carried in a laminated state to thereby enable to promote performance of storing the brake pad and performance of handling thereof.
In order to achieve the above-described object, according to the present invention, there is provided a brake pad wear detecting apparatus including a probe case attached to a back plate and a probe mounted to the probe case and fixedly positioned to a predetermined position relative to a lining for detecting wear of a brake pad and outputting a wear detecting signal when a wear amount of the lining reaches a predetermined value,
wherein the probe case includes a first elastic locking piece achieving coupling with the back plate and a second elastic locking piece for fixedly positioning the probe, and
wherein the first elastic locking piece is constructed so that when the probe case is attached to the back plate in a state of not mounting the probe, the first elastic locking piece is brought into a tacked state of being coupled to the back plate by elastic deformation and when the probe is mounted to the probe case in the tacked state, the elastic deformation of the first elastic locking piece is restricted by the probe and the probe case is brought into a locked state in which the probe case cannot be detached from the back plate, and
wherein the second elastic locking piece includes a release operating portion for disengaging engagement with the probe.
Further, according to the brake pad wear detecting apparatus having the above-described constitution, when the engagement between the second elastic locking piece and the probe is disengaged by operating the release operating portion of the probe case, the probe can be detached from the probe case. Further, the probe case in the state of not mounting the probe by detaching the probe is brought into the tacked state capable of releasing engagement of the first elastic locking piece for coupling the probe case and the back plate, while the back plate and the probe case can be simply detached from the back plate.
That is, according to the above-described brake pad wear detecting apparatus, the probe case is not integrated to the brake pad, and the probe case and the probe can be simply attached to and detached from the brake pad, if necessary.
Therefore, it is not necessary to incorporate a step of attaching the probe case for fabricating the brake pad. Further, when the probe case is stored or carried, the probe case can be kept in a state of being detached from the brake pad, and when the brake pad is replaced, the probe case can be detached from the used brake pad and utilized again.